Blower Fan

[plfx4]

My blower fan only run on the 3rd and 4th gear.
Should I replace the resistor or I should consider something else.
Some says that if it's the resistor it will only work on the fourth one...
Help
Thanks

[SeattleJeremy]

Blower motor resistors contain controls that determine air settings, each control on your dash relates to a resistor inside the Blower Motor resistor module.

The fact 1-2 don't work, is enough to say replacing the blower motor resistor module should fix the problem.